Cutter knife for hemstitching machines



Sept. 10, 1929. E. BUN IN 1,727,807

CUTTER KNIFE FOR .HEMSTITCHING HACHINES Filed Dec. 1, 1928 2 Sheets-Sheet 1 26 38 INVENTO 36 E LL15 u/w/v.

E BY

ATTOR EY Sept. 10, 1929. E. BUNIN 1,727,307

CUTTER KNIFE FOR HEMSTITCHING IACHINES Filed Dec. 1, 1928 2 Sheets-Sheet 2 INVENT Fj fE ELL/5 u/v/N.

Patented Sept. 10, 1929.

v UNITED STATES PATENT OFFICE."

ELLIS IB'UNIN, OF BROOKLYN NEW YORK, ASSIGNOR 'I'O ELLIS BUN IN, DAVID BUN IN, AND AARON GALLENS, A PARTNERSHIP DOING BUSINESS AS BUNIN, BUNIN &

COMPANY, OF NEW YORK, N. Y.

CUTTER KNIFE FOR HEIVISTITOHING MACHINES.

Application filed December 1, 1922. 1 Serial No. 323,155.

This invention relates generally to sewing machines and has more'particular reference to a novel single knife adjustable cutter for hemstitching machines.

5 The invention has for an object the provision of a device of the class mentioned, which is of simple durable construction, desirable in use and eliicient in action, and which can be manufactured and sold at a reasonable cost.

The invention proposes the use of a knife holder bracket arranged for attachment on the presser foot bar of a hemstitching machine and having inclined slots for receiving a holding stud for holding a knife holder so that it may be raised from operative to an inoperative position. The knife holder is pivotally mounted upon the stud and connects with some rocking shaft of the hemstitching machine for receiving a rocking motion. A single straight edged knife is attached on one end of the knife holder and is arranged for assuming a position in the path of motion of goods being sewn and desired to be cut.

The presence of cutting knives in hemstitching machines is known to be old, but these knives work very unsatisfac-torily. In

one instance a pair of crossed knives acting 30 like a shear is used, one of the blades being held stationary and the other oscillated to shear the goods. The greatest trouble found with this type of knife is that when corners are turned a true corner cannotbe formed because the scissors out along any point of their length. In recent years the practice of hemstitching providing many turns and corners is very common and this type of knife falls down in that the corners produced are sharp and therefore are unsatisfactory.

A second type of knife used is a vertical knife which reciprocates up and down. While this knife may cut sharp corners it falls down in that after a short period of use it has a pulling tendency upon the goods being cut. The reason for this is that in order to obtain true cutting, the knife must not move in a vertical direction, but must be moved slightly forwards and downwards at 5 the same time. A pull upon the cloth produced by this knife. is not very pleasant to the operator of the machine who must hold the goods against the pull for directing it in a straight line. Moreover, a rough and ragged edge is produced by this type of cutting. It is generally known that good cutting cannot be obtained by merely pulling or pushing a knife thru goods.

The instant invention proposes a knife normally positioned at a slight incline with respect to the vertical and moves simultaneously, horizontally and vertically, or more specifically stated, forwards and downwards for obtaining theoretical perfect cutting. The goods are fed towards the knife in a horizontal plane and the specified motion of the knife is obtained by moving the knife thru an arc of a circle.

The knife holder is preferably connected with the back plunger carrier shaft of the hemstitching machine which rocks three times for each time the feeders move the goods being sewn forwardsabout of an inch. The actual cutting takes place on the down stroke of the'knife and a specific point along the length of knife after it. cuts the goods moves out of the vertical from the cut, because it is moving in the arc of a circle. Thus when the knife returns in its up stroke, the goods is not pulled because it has already been cut and the knife merely idles back.

For further comprehensionof the invention, and of the objects and advantages thereof, reference'will be had to the following description and accompanying drawing, and the appended claims in which the various novel features of the invention are more particularly set forth. 7

In the accompanying drawing forming a material part of this disclosure:

Fig. 1 is an end view of a hemstitching machine provided with a cutting knife con structed according to this invention.

Fig. 2 is a fragmentary rear 'elevational View thereof.

Fig. 8 is a plan view of the knife holder bracket, the knife holder with a knife, and a pivoting stud.

Fig. 4 is a side elevational view of Fig. 3.

Fig. 5 is a vertical sectional view, taken on the line 55 of Fig. 4, and

Fig. 6 is a view similar to Fig. 4, but showing the knife in an operative position.

The reference numeral 10 indicates generally. the bed of a hemstitching machine having a sewing head 11. The bed 10 is shown with a bobbin cover plate 12 upon which the foot 13 rests. ried by the presser foot bar 14 of the sewing lead. The hemstitching machine shown is of standard design and the more important parts thereof. shown on the drawing are,

thread tension rollers 15, back plunger carrier shaft 16, needle vibrating bars 17, thread tension members 18, backplunger 19, front plunger 20, and needles 21.

A knife holder bracket 22 is attached upon thepresser foot bar 14. This knife holder bracket has an aperture 23 thruwhich the presser footbar passes, and a set screw 24 for fastening it in place. The knife holder bracket 22 also has parallel walls 25 with a large inclined slot 26 in one wall and a smaller width inclined slot 27 in the opposite wall. These slots are aligned with each other for receiving a stud 28 which has a flattened por tion 29 engaging in the smaller slot 27. The diameter of the stud is such that it may freely move in the larger slot 26. A knife holder 30 is pivoted intermediate of its ends on the stud 28 and is positioned between the parallel walls 25.

A stud clamp 31 threadedly engages upon one end of the stud 28 for clamping the stud in any desired position along these slots. This stud clamp is provided with a finger handle 32 to aid in the manual manipulation thereof. The rear end of the knife holder is reduced as may be seen in Fig. 3 and this end may be called the tail end and is designated by numeral 33. The front end 34 of the knife holder is formed with a central slot 35 and a knife 36 engages in this slot and is held in place by a screw 37. This knife, has a. straight cutting edge 38 normally slightly inclined with respect to the vertical. A lug 39 is integral on the top side of the bracket 22.

The inclined slots in the parallel walls of the, bracket slope upwards from the front towards the rear and the stud 28 is at the rear of this slot as shown in Figs. 1 2, and 4. The knife 36 is in a position raised above the goods, then, so that no cutting is accomplished. Of course, the knife may oscillate or remain stationary and in both conditions be inoperative. hen the stud 28 is at the front of the inclined slots as shown in Fig. 6, the knife 36 is in a lowered positionas seen in this igure and when it is oscillated operates and cuts. Dot dash lines 40 indicate the goods being cut and dot dash lines 41 indicate the top position of the knife and knife holder during its cutting operation.

A collar 42 is fixed on the back plunger car- This foot is car-' rier shaft 16 and a collar bracket 43 is attached on this collar. Connector arm 44 is pivotally attached on its top end on the end of a bracket 43 and at its bottom end is provided with a stop screw 45.. A slid-able collar 46 is engaged upon the connector arm 44 and is formed with a top lug 47. A spring 48 acts between the lug 47 and the stop screw for urging the collar 46 downwards against the knife holder tail 33. A. link 49 is pivotally connected at one end on the lug 39 of the knife holder bracket and at its other end on the connector arm 44. This link holds the bot-tom of the connector arm from swinging away, but permits the connector arm to reciprocate up and down.

Figsl, 2 and 4show the stud 28 at the rear end of the inclined slots 26, 2'? so that the knife 36-is in an inoperative position. As the hemstitching machine is operated and goods sewn therewith the back plunger carrier shaft 16 rocks causing the connector arm 44 to reciprocate up and down. This motion may or may not be transmitted to the knife holder tail 33 when the knife holder is locked in this position. The collar 46 may be raised by the tail 33, if the knife were stopped in its upstroke, so as not to touch the stop screw 45 thus leaving a space 50 between the tail 33 and the stop screw. As the connector arm moves to its top position this space is closed, but the connector arm does not mov sufiiciently to move the knife holder. On

the down stroke of the connector arm the spring 48 is merely stretched and allows the space 50. y

The stud clamp 31 may be loosened and the stud 28 allowed to move to the front of the inclined slots. Then the knife 36 lies in the path of motion of the goods as seen in Fig. 6 and extends thru a slot in the bobbin cover plate 12. Now, when the back plunger carrier shaft 16 oscillates, motion will be transmitted to the knife holder tail 33 for oscillating the knife holder and moving the cutting knife 36. As before stated in the particular hemstitching machine shown, the back plunger carrier shaft 16 will oscillate three times for each time that thefeeders not shown in the drawing move the goods being sewn forwards about of an inch but this is not a limitation since the cutter would operate with other ratios of these parts.

Examining Fig. 6 closely it will be noticed that as the knife 36 moves in the arc of a circle with the stud 28 as a pivot it cuts the goods on a down stroke then idles on the up stroke since the goods is out. No pull is produced on the goods no matter how delicate it may be, such as georgette or other fine goods, since the cutting points on the knife simultaneously move downwards and forwards relative to the goods. It should be noticed that the cutting knife 36 may be moved into operative or inoperative position without removing it from the machine. The vertical reciprocating knife referred to on page 2 of this specification cannot be moved into an inoperative position without removal from the machine. This is a great shortcoming with present day hemstitching, since it is quite often necessary to start and stop the knife for cutting the hemstitiching at certain portions and not at others.

While I have illustrated and described my invention with some degree of particularity, I realize that in practice Various alterations therein may be made. I therefore reserve the right and privilege of changing the form of the details or otherwise altering the arrangement of the correlated parts without departing from the spirit or the scope of the appended claims.

Having thus described my invention what I claim as new and desire to secure by United States Letters Patent is:

1. A cutter for hemstitching machines having a presser foot bar, comprising a knife holder bracket for attachment on the presser foot bar, and having an inclined slot sloping upwards towards the rear, a knife holder pivotally mounted on a stud slidable within the said inclined slot and arranged for assuming fixed positions, a knife attached on the front of the knife holder, and a means for connecting the rear of the knife holder with an oscillating part of the hemstitching machine for oscillating the knife for operative cutting in one of the said fixed positions, and inopera tive with respect to cutting in a difierent of the said fixed positions.

2. A cutter for hemstitching machines having a presser foot bar, comprising a knife holder bracket for attachment on the presser foot bar, and having an inclined slot sloping upwards towards the rear, a knife holder pivotally mounted on a stud slidable within the said inclined slot and arranged for assuming fixed positions, a knife with a straight inclined cutting edge attached on the front of the knife holder and a means for connecting the rear of the knife holder with an oscillating part of the hemstitching machine for oscillating the knife for operative cutting in one of the said fixed positions, and inoperative with respect to cutting in a different of the said fixed positions.

3. A cutter for hemstitching machines having a presser foot bar, comprising a knife holder bracket for attachment on the presser foot bar, and having parallel walls with inclined slots sloping upwards towfards the rear, a knife holder pivotally mounted on a stud slidable within the said inclined slots and arranged for assuming fixed positions, a knife attached on the front of the knife holder, and a means for connecting the rear of the knife holder with an oscillating part of the hemstitching machine for oscillating the knife for operative cutting in one ofthe said fixed positions, and inoperative with respect to cutting in a different of the said fixed positions.

4:. A cutter for 'hemstitchingmachines having a presser foot bar, comprising aknife holder bracket for attachment on the presser foot bar, andhaving parallel walls with insaid means consisting of an arm for connec-- Y tion with abracket fixed on the oscillating part of the hemstitching machine, a screw projecting from the arm, a collar slidable on the arm, and a spring acting between the collar and screw, and the rear of the knife holder being abutted by the collar and urged to wards the screw.

5. A cutter for hemstitching machines having a presser foot bar, comprising a knife holder bracket for attachment on the presser foot bar, and having parallel walls with inclined slots sloping upwards towards the rear,

a knife holder pivotally mounted on a stud slidable within the said inclined slots and arranged for assuming fixed positions, a knife attached on the front of the knife holder, and a means for connecting the rear of the knife holder with an oscillating part of the hemstitching machine for oscillating the knife for operative cutting in one of the said fixed positions, and inoperative with respect to cutting in a different of the said fixed positions, said means consisting of an arm for connection with a bracket fixed on the oscillating part of the hemstitching machine, a screw projecting from the arm, a collar slidable on the arm, and a spring acting between the collar and screw, and the rear of the knife holder being abutted by the collar and urged towards the screw, a link being pivotally connected between the said arm and the knife holder bracket.

6. A cutter for hemstitching machines having a presser foot bar, comprising a knife holder bracket for attachment on the presser foot bar, and having an inclined slot sloping upwards towards the rear, a knife holder pivotally mounted on a stud slidable within the said inclined slot and arranged for, assum-, ing fixed positions by reason of a stud clamp with a finger handle, a knife attached on the front of the knife holder, and a means for connecting the rear of the knife holder with an oscillating part of the hemstitching maof Nevember, 1928.

chine'for oscillating the knife for operative cutting in one of the said fixed positions, and inoperative with respect to cutting in a, different of the said fixed positions.

Signed at NeW Y.ork,-in the county of New York and State of New'York, this 23rd day ELLIS BUNIN. 

